(a) Field of the Invention
The present invention relates to a seven-speed powertrain of an automatic transmission for a vehicle.
(b) Description of the Related Art
Powertrains for automatic transmissions have been developed in different ways depending on the vehicle company, and whether a four-speed or five-speed powertrain is used. Also, six-speed automatic transmissions have been recently developed and adopted to some vehicles, and seven-speed automatic transmissions are also being developed.
However, while some existing seven-speed powertrains may realize seven forward speeds and one reverse speed, there can be problems in that overall length of the powertrain is long since the powertrain is formed by adding one brake to a conventional six-speed automatic transmission and all elements are arranged in a length direction on one shaft. Also problems can arise in that durability and design freedom are poor since a load acting on a planetary gear and a clutch is increased due to an increase of a shift ratio.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.